Third-rail telephone



C. W. WALKER THIRD RAIL TELEPHONE 2 Sheets-Sheet 1 tlmw Dec. 1924- 1,520,619

' c. w. WALKER THIRD RAIL TELEPHONE Filed Sept. 26, 2 Sheets-Sheet 2 WW -ZUZUQZZ) Patented Dec. v23, 1924.

- UNITED STATES PATENT OFFICE- CHARLES WALKER, OF JERSEY CITY, NEW JERSEY; DAVID N. E. CAMPBELL, OF

BROOKLYN, NEW YORK, ADMINISTRATOR OF THE SAID CHARLES W. WALKER,

DECEASED.

THIRD-RAIL Application filed September To all whom it may concern:

Be it known that T, CHARLES W. WALKER, a citizen of the United States, residing at Jersey City, in the county of Hudson and State of New Jersey, have invented certain new and useful Improvements in Third- Rail Telephones, of which the following is a specification.

This invention relates to telephony and has special reference to apparatus for receiving telephonic communications on moving trains.

One important object of the inventlon 1s to improve the general construction of devices ofthis character.

It is a well known and understood fact that the current required under ordinary circumstances to produce telephonic communications is very slight, and of low voltage. Also it is well understood that any variations in the resistance of a conductor with such low currents such as would-be produced by a sliding or rolling contact moving along a rail, or wire will so effect the receiver of the instrument that the noise produced will drown the spoken sounds.

A secondimportant object of the invention is to provideian improved arrangement of apparatus wherein a relatively high tension current can be used as the primary current through a wire or rail placed alongside of a railroad train and a low tension current used on the train for the reception or transmittal of the facts, or words.

A third important object of theinvention is to provide an improved contact apparatus in such a device.

With the above and other objects in view as will be hereinafter apparent the invention consists in general ofcerta1n novel details of construction and combinations of parts hereinafter fully described, illus trated in the accompanying drawings and specifically claimed. I In the accompanying drawings like characters of reference indicate like parts in the several views, and p Figure 1 is a view showing a portion of a railroad car with the apparatus in position thereon, the car and parts not directly connected with'the apparatus being indicated in broken lines while those parts directly concerned being indicated in full lines.

TELEPHONE.

26,1922. Serial no. 590,687.

Figure 2 is a diagrammatical view of the wire in such a system.

Figure 3 is an enlarged detail view of the contact shoes and their supports, the view being an end elevation.

Figure 4 is a detail sectionl on the line 44 of Figure 3.

Figure 5 is a detail section on the line 5-5 of Figure 4:.

Figure 6 is a detail section on the line 6-6 of Figure 4. i In carrying out the objects of this invention there is preferred to use'a main circuit wherein a relatively high tension battery B is connected in series with a receiver 10 and transmitter 11 by means of line wires 12 which are supported along the railroad track on brackets 13 carried on bases 14 secured. to the ties T. These brackets 13 are insulatin brackets of the usual type.

On the tram and fixed to some part of the car as indicated at C in Figure 4 is an upper, or stationary housing 15 having a bracket 16 by means of which it may be secured to the part C. Depending from the lower end of this housing are guide bars 17 which pass through ears 18 on a lower housing 19 having its lower end open. Extending vertically and centrally of this lower housing is a pair of spaced guide tubes 20 having insulating sleeves 21 within them, whereln move the stems 22 of contact shoes. Each of these contact shoes consists of a pair of diverging arms 23 which are connected by spring members 24 adapted to bear on a respective wire 12. This member 24 is forced down on the wire by a coil spring 25 surrounding the stem 22 and bearing at its upper end against the lower end of the sleeve 21. The sleeve 21 is provided with a guide slot 26 which registers with a somewhat larger guide slot 27 formed in the guide 20. Through these slots passes'a contact pin28 bearing against a spring contact 29 which is connected to a post 30 and passing through an insulating sleeve 31 in head, or top housing 19. On the upper end of each of these insulating sleeves is a contact 32 which engages a contact 33 formed on the bottombinding post 34: passing through a sleeve 35 of insulating material in the bottom of the housing 15. From the binding post a wire 36 leads to a resistance coil 37 and from the resistance coil awire 38 leads to themagnet 39 of a telephone receiver-transmitter 40. Supported above this receiver-transmitter 40 is a telephone mitter 40 and that such variations as 'may.

- be simply caused by the equalities of contact between the contacts 24 and wires 12 will, by reason of the constant pressure being so slight as not to interfere with the variations caused in the circuit by the voice. Consequently the vibrations of the diaphragm in the receiver 40 will eflect the diaphragm in the receiver-transmitter 41 and vary. the current in the secondary, or train supported circuit. It is to be understood that the reoeiver and transmitter 41 and 40 are of any preferred type such as may be used for transmitting in either direction.

There has thus been provided a simple and 'eflicient device of the kind described and for the purposes specified.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the spirit thereof. It is not, therefore, desired to confine the invention to the'exact form herein shown and described, but it is desired to include all such as properly come within the S00 e claimed.

aving thus described the what is claimed as new, is

1. In a device of the kind described, a main circuit including track wires and a train supportedaeceiver transmitter and a secondary circuit supported on the train and including a transmitter in receiving proximity to said receiver-transmitter, a second recelver and a second transmitter.

2. In a device of the kind described, the combination with a pair of line wires supported beside a track, of train supported invention contacts constantly urged into contact with said wires, a receiver-transmitter having electrical connection wlth sa d contacts, and a recelvmg circuit including a transmitter having its mouth in close proximity and in alinement with tlMJIIlOllth of said receivertransmitter.

3. In a device of the kind described, an upper housing a lower housing, apair of contact shoes slidable-vertically in the lower housing, spring means urging said contact shoes downward, a receiver-transmitter in the upper housing, and conductor means connecting said receiver-transmitter with said shoes and including a slidingcontact.

4. In a device of the kind described, an

upper housing, a lower housing, a pair of guide sleeves in said lower hous1ng,-1nsulatmg bushings in said gulde sleeves, said .bushings and sleeves having alined guide connections between said posts and receivertransmitter.

5. In a device of the kind described, an upperhousing, "a lower housing, a pair of guide sleeves in said lower housing, insulating bushings in said guide sleeves, said bushings and sleeves having aline'd guide slots, insulated posts in the upper and lower housing, a stem slidably mounted in each of the insulating bushings, a spring con-- tact member carried by each of said posts, and extending down along the guide sleeves opposite the respective guide openings, contact pins projecting through said openings from said stems and engaging said contact springs, a contact shoe carried on the lowerend over each stem, springs urging said contact shoes downward, a receiver-transmltter 1n the upper housing, and electrical connections between said posts and receiver, said.

electrical connections including binding posts extending through the bottom and upper housing and insulated therefrom, the lower ends of said binding posts being in contact with the upper ends of the first mentioned posts, resistance coils in the upper housing, a connection between each binding post and the respective resistance.

coil, and a connection between each resistance coil and the recewer-transmatter.

6. In a device of the kind described, an

upper housing, a lower housing, a pair of guide sleeves in said lower housing insulating bushings in said guide sleeves, said bushings and sleeves having alined guide slots, insulated posts in the upper and lower housing, a stern slidably mounted in each of the insulating bushings, a springcontact member carried by each of said posts, and

'extending down along the guide sleeves opposite the respective guide -openings, contact pins projecting through said openings from said stems and engaging said contact springs, a contact shoe carried on the lower end over each stem, springs urging-said contact shoes downward, a receiver-transmitter in the upper housing, and electrical connections between said posts and receiver-transmitter, said electrical connections including binding posts extending through the bottom in alinement with S&i& receiver-transmitter and upper housing and insulated therefrom, and having its mouth in proximity to the the lower ends of said binding posts being mouth of the receiver-transmitter.

in contact with the upper ends of the first In testimony whereof I eflix my signa- Efi mentioned posts, resistance coils in the upturein presence of two witnesses.

per housing, a connection between each binding post and the respective resistance CHARLES WALKER coil, 3. connection between each resistance Witnesses:

coil and the receiver-transmitter, and a ROBERT WILLIAMS, 1 transmitter mounted in the upper housing ARTHUR BROWN. 

